3. GREEN DAY “21st Century Breakdown” (Reprise) Green Day’s second rock opera is more ambitious than “American Idiot”: richer, more diverse, more urgent, more flat-out tuneful and also more confusing. The ultimate target of the songs’ rage and frustration can be unclear — the most pointed song can only ask “Do you know your enemy?” — but the ambition and the spirit of punky rebellion are strong. (Jon Pareles, New York Times)